The Geysers, California – A magnitude 4.1 earthquake struck near The Geysers geothermal field Saturday afternoon, followed minutes later by a magnitude 2.9 tremor in northern Sonoma County.
According to the U.S. Geological Survey (USGS), the M4.1 quake occurred at 9:22 a.m. PST (17:22:55 UTC), approximately 6 kilometers north-northwest of The Geysers and about 12 miles east of Cloverdale. The quake was recorded at a shallow depth of less than 1 kilometer.
A second earthquake, measuring magnitude 2.9, was reported at 9:23 a.m. PST, roughly 4 kilometers north-northwest of The Geysers at a depth of 3.2 kilometers. The events occurred within minutes of each other, prompting what seismologists describe as a short seismic sequence.
USGS ShakeAlert data indicated an initial magnitude estimate of 4.3 before finalizing at 4.1. The quake remained below the threshold required to trigger a Wireless Emergency Alert to cell phones.
Community intensity reports showed weak shaking (MMI II) in Cloverdale, approximately 12 miles from the epicenter. Santa Rosa and Ukiah reported little to no shaking.
The Geysers region, located in Sonoma and Lake counties, is one of the most seismically active areas in California due to both natural faulting and geothermal energy production operations.
No injuries or structural damage were immediately reported as of Saturday afternoon.
Minor earthquakes are common in the area and are frequently monitored by the California Integrated Seismic Network and USGS.
The brief shaking may have been noticeable to residents, students, and remote workers across northern Sonoma County during the late-morning hours.
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